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Message-ID: <ZIMzkkxp0RFgjIwW@kernel.org>
Date: Fri, 9 Jun 2023 11:13:38 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: John Garry <john.g.garry@...cle.com>,
Will Deacon <will@...nel.org>,
James Clark <james.clark@....com>,
Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...aro.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
Kan Liang <kan.liang@...ux.intel.com>,
German Gomez <german.gomez@....com>,
Ali Saidi <alisaidi@...zon.com>,
Jing Zhang <renyu.zj@...ux.alibaba.com>,
Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
Miguel Ojeda <ojeda@...nel.org>,
ye xingchen <ye.xingchen@....com.cn>,
Liam Howlett <liam.howlett@...cle.com>,
Dmitrii Dolgov <9erthalion6@...il.com>,
Yang Jihong <yangjihong1@...wei.com>,
K Prateek Nayak <kprateek.nayak@....com>,
Changbin Du <changbin.du@...wei.com>,
Ravi Bangoria <ravi.bangoria@....com>,
Sean Christopherson <seanjc@...gle.com>,
Andi Kleen <ak@...ux.intel.com>,
"Steinar H. Gunderson" <sesse@...gle.com>,
Yuan Can <yuancan@...wei.com>,
Brian Robbins <brianrob@...ux.microsoft.com>,
liuwenyu <liuwenyu7@...wei.com>,
Ivan Babrou <ivan@...udflare.com>,
Fangrui Song <maskray@...gle.com>,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-perf-users@...r.kernel.org, coresight@...ts.linaro.org
Subject: Re: [PATCH v2 02/26] perf thread: Make threads rbtree non-invasive
Em Thu, Jun 08, 2023 at 04:27:59PM -0700, Ian Rogers escreveu:
> Separate the rbtree out of thread and into a new struct
> thread_rb_node. The refcnt is in thread and the rbtree is responsible
> for a single count.
You stated what you did, but didn't spell out the reason, can you
ellaborate on this so that the git history becomes more helpful for new
contributors?
- Arnaldo
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
> tools/perf/builtin-report.c | 2 +-
> tools/perf/builtin-trace.c | 2 +-
> tools/perf/util/machine.c | 101 +++++++++++++++++++++++-------------
> tools/perf/util/thread.c | 3 --
> tools/perf/util/thread.h | 6 ++-
> 5 files changed, 73 insertions(+), 41 deletions(-)
>
> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> index 92c6797e7cba..c7d526283baf 100644
> --- a/tools/perf/builtin-report.c
> +++ b/tools/perf/builtin-report.c
> @@ -911,7 +911,7 @@ static int tasks_print(struct report *rep, FILE *fp)
> nd = rb_next(nd)) {
> task = tasks + itask++;
>
> - task->thread = rb_entry(nd, struct thread, rb_node);
> + task->thread = rb_entry(nd, struct thread_rb_node, rb_node)->thread;
> INIT_LIST_HEAD(&task->children);
> INIT_LIST_HEAD(&task->list);
> thread__set_priv(task->thread, task);
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 62c7c99a0fe4..b0dd202d14eb 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -4348,7 +4348,7 @@ DEFINE_RESORT_RB(threads, (thread__nr_events(a->thread->priv) < thread__nr_event
> struct thread *thread;
> )
> {
> - entry->thread = rb_entry(nd, struct thread, rb_node);
> + entry->thread = rb_entry(nd, struct thread_rb_node, rb_node)->thread;
> }
>
> static size_t trace__fprintf_thread_summary(struct trace *trace, FILE *fp)
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index a1954ac85f59..cbf092e32ee9 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -43,7 +43,8 @@
> #include <linux/string.h>
> #include <linux/zalloc.h>
>
> -static void __machine__remove_thread(struct machine *machine, struct thread *th, bool lock);
> +static void __machine__remove_thread(struct machine *machine, struct thread_rb_node *nd,
> + struct thread *th, bool lock);
> static int append_inlines(struct callchain_cursor *cursor, struct map_symbol *ms, u64 ip);
>
> static struct dso *machine__kernel_dso(struct machine *machine)
> @@ -72,6 +73,21 @@ static void machine__threads_init(struct machine *machine)
> }
> }
>
> +static int thread_rb_node__cmp_tid(const void *key, const struct rb_node *nd)
> +{
> + int to_find = (int) *((pid_t *)key);
> +
> + return to_find - (int)rb_entry(nd, struct thread_rb_node, rb_node)->thread->tid;
> +}
> +
> +static struct thread_rb_node *thread_rb_node__find(const struct thread *th,
> + struct rb_root *tree)
> +{
> + struct rb_node *nd = rb_find(&th->tid, tree, thread_rb_node__cmp_tid);
> +
> + return rb_entry(nd, struct thread_rb_node, rb_node);
> +}
> +
> static int machine__set_mmap_name(struct machine *machine)
> {
> if (machine__is_host(machine))
> @@ -214,10 +230,10 @@ void machine__delete_threads(struct machine *machine)
> down_write(&threads->lock);
> nd = rb_first_cached(&threads->entries);
> while (nd) {
> - struct thread *t = rb_entry(nd, struct thread, rb_node);
> + struct thread_rb_node *trb = rb_entry(nd, struct thread_rb_node, rb_node);
>
> nd = rb_next(nd);
> - __machine__remove_thread(machine, t, false);
> + __machine__remove_thread(machine, trb, trb->thread, false);
> }
> up_write(&threads->lock);
> }
> @@ -605,6 +621,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine,
> struct rb_node **p = &threads->entries.rb_root.rb_node;
> struct rb_node *parent = NULL;
> struct thread *th;
> + struct thread_rb_node *nd;
> bool leftmost = true;
>
> th = threads__get_last_match(threads, machine, pid, tid);
> @@ -613,7 +630,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine,
>
> while (*p != NULL) {
> parent = *p;
> - th = rb_entry(parent, struct thread, rb_node);
> + th = rb_entry(parent, struct thread_rb_node, rb_node)->thread;
>
> if (th->tid == tid) {
> threads__set_last_match(threads, th);
> @@ -633,30 +650,39 @@ static struct thread *____machine__findnew_thread(struct machine *machine,
> return NULL;
>
> th = thread__new(pid, tid);
> - if (th != NULL) {
> - rb_link_node(&th->rb_node, parent, p);
> - rb_insert_color_cached(&th->rb_node, &threads->entries, leftmost);
> + if (th == NULL)
> + return NULL;
>
> - /*
> - * We have to initialize maps separately after rb tree is updated.
> - *
> - * The reason is that we call machine__findnew_thread
> - * within thread__init_maps to find the thread
> - * leader and that would screwed the rb tree.
> - */
> - if (thread__init_maps(th, machine)) {
> - rb_erase_cached(&th->rb_node, &threads->entries);
> - RB_CLEAR_NODE(&th->rb_node);
> - thread__put(th);
> - return NULL;
> - }
> - /*
> - * It is now in the rbtree, get a ref
> - */
> - thread__get(th);
> - threads__set_last_match(threads, th);
> - ++threads->nr;
> + nd = malloc(sizeof(*nd));
> + if (nd == NULL) {
> + thread__put(th);
> + return NULL;
> + }
> + nd->thread = th;
> +
> + rb_link_node(&nd->rb_node, parent, p);
> + rb_insert_color_cached(&nd->rb_node, &threads->entries, leftmost);
> +
> + /*
> + * We have to initialize maps separately after rb tree is updated.
> + *
> + * The reason is that we call machine__findnew_thread within
> + * thread__init_maps to find the thread leader and that would screwed
> + * the rb tree.
> + */
> + if (thread__init_maps(th, machine)) {
> + rb_erase_cached(&nd->rb_node, &threads->entries);
> + RB_CLEAR_NODE(&nd->rb_node);
> + free(nd);
> + thread__put(th);
> + return NULL;
> }
> + /*
> + * It is now in the rbtree, get a ref
> + */
> + thread__get(th);
> + threads__set_last_match(threads, th);
> + ++threads->nr;
>
> return th;
> }
> @@ -1109,7 +1135,7 @@ size_t machine__fprintf(struct machine *machine, FILE *fp)
>
> for (nd = rb_first_cached(&threads->entries); nd;
> nd = rb_next(nd)) {
> - struct thread *pos = rb_entry(nd, struct thread, rb_node);
> + struct thread *pos = rb_entry(nd, struct thread_rb_node, rb_node)->thread;
>
> ret += thread__fprintf(pos, fp);
> }
> @@ -2020,10 +2046,14 @@ int machine__process_mmap_event(struct machine *machine, union perf_event *event
> return 0;
> }
>
> -static void __machine__remove_thread(struct machine *machine, struct thread *th, bool lock)
> +static void __machine__remove_thread(struct machine *machine, struct thread_rb_node *nd,
> + struct thread *th, bool lock)
> {
> struct threads *threads = machine__threads(machine, th->tid);
>
> + if (!nd)
> + nd = thread_rb_node__find(th, &threads->entries.rb_root);
> +
> if (threads->last_match == th)
> threads__set_last_match(threads, NULL);
>
> @@ -2032,11 +2062,12 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
>
> BUG_ON(refcount_read(&th->refcnt) == 0);
>
> - rb_erase_cached(&th->rb_node, &threads->entries);
> - RB_CLEAR_NODE(&th->rb_node);
> + thread__put(nd->thread);
> + rb_erase_cached(&nd->rb_node, &threads->entries);
> + RB_CLEAR_NODE(&nd->rb_node);
> --threads->nr;
>
> - thread__put(th);
> + free(nd);
>
> if (lock)
> up_write(&threads->lock);
> @@ -2044,7 +2075,7 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
>
> void machine__remove_thread(struct machine *machine, struct thread *th)
> {
> - return __machine__remove_thread(machine, th, true);
> + return __machine__remove_thread(machine, NULL, th, true);
> }
>
> int machine__process_fork_event(struct machine *machine, union perf_event *event,
> @@ -3167,7 +3198,6 @@ int machine__for_each_thread(struct machine *machine,
> {
> struct threads *threads;
> struct rb_node *nd;
> - struct thread *thread;
> int rc = 0;
> int i;
>
> @@ -3175,8 +3205,9 @@ int machine__for_each_thread(struct machine *machine,
> threads = &machine->threads[i];
> for (nd = rb_first_cached(&threads->entries); nd;
> nd = rb_next(nd)) {
> - thread = rb_entry(nd, struct thread, rb_node);
> - rc = fn(thread, priv);
> + struct thread_rb_node *trb = rb_entry(nd, struct thread_rb_node, rb_node);
> +
> + rc = fn(trb->thread, priv);
> if (rc != 0)
> return rc;
> }
> diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
> index d949bffc0ed6..38d300e3e4d3 100644
> --- a/tools/perf/util/thread.c
> +++ b/tools/perf/util/thread.c
> @@ -66,7 +66,6 @@ struct thread *thread__new(pid_t pid, pid_t tid)
>
> list_add(&comm->list, &thread->comm_list);
> refcount_set(&thread->refcnt, 1);
> - RB_CLEAR_NODE(&thread->rb_node);
> /* Thread holds first ref to nsdata. */
> thread->nsinfo = nsinfo__new(pid);
> srccode_state_init(&thread->srccode_state);
> @@ -84,8 +83,6 @@ void thread__delete(struct thread *thread)
> struct namespaces *namespaces, *tmp_namespaces;
> struct comm *comm, *tmp_comm;
>
> - BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));
> -
> thread_stack__free(thread);
>
> if (thread->maps) {
> diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
> index 86737812e06b..3b3f9fb5a916 100644
> --- a/tools/perf/util/thread.h
> +++ b/tools/perf/util/thread.h
> @@ -29,8 +29,12 @@ struct lbr_stitch {
> struct callchain_cursor_node *prev_lbr_cursor;
> };
>
> +struct thread_rb_node {
> + struct rb_node rb_node;
> + struct thread *thread;
> +};
> +
> struct thread {
> - struct rb_node rb_node;
> struct maps *maps;
> pid_t pid_; /* Not all tools update this */
> pid_t tid;
> --
> 2.41.0.162.gfafddb0af9-goog
>
--
- Arnaldo
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